Improvement in metallic arch-bridges



J. ABBD'I'T.

METALLIC ARCH BRIDGES.

No.184=,490, Patented Nov.2' 1,1876,

UNITED STATES Prnrnlvr OFFICE.

JOB ABBOTT, OF CANTON, OHIO, ASSIGNOR TO WROUGHT IRON BRIDGE COMPANY, OFSAME PLACE.

IMPROVEMENT IN METALLIC ARCH-BRIDGES.

Specification forming part of Letters Patent No. 184,490, dated November21, 1876; application filed August 19, 1876.

To all whom it may concern:

Be it known that I, JOB ABBOTT, of Canton, in the county of Stark andState of Ohio, have invented certain new and useful Improvements inArch-Bridges: and that the following is a full, clear and exactspecification thereof, which will enable others skilled in the art tomake and use the said invention.

My invention is designed to obviate the difficulty experienced inconstructing longspan arch-bridges, of getting the diagonal ties to lieat or near the proper angle, to secure stiffness and economy withoutmaking the panels of too great length, as well as to effect a saving ofmaterial by reducing the number of posts required; and to this end itconsists in connecting the diagonal ties in each panel of an arch-bridgeat or near the center of the panel and uniting this point of supportwith the upper and lower chords of the girder; also in securing thecenter of-the intermediate post of an arch bridge by means of rods fromsaid central diagonal-tie connections, thus reducing the effectivelength and increasing the stiffness of said post, as

is hereinafter more fully shown.

The accompanying drawing is a view of the central panels of anarch-bridge embodying my invention.

'A is an arch of any desired form of section. B is the lower chord, andO D O are the girder-posts, which are usually made widest laterally, toaid in holding the arch against lateral deflection. K is the centerdiagonal connection, which is here shown as being made of two plates ofcircular form, between which the eyes on the diagonal rods are securedby bolts run through the plates and eyes, although a pin-and-eyeconnection may be used instead, if preferred, especially when doubleties are used. The diagonal ties E F G H are made in twolengths, thelower parts EG being secured by eyes to the lower chords B and centerplates K, and the upper parts F H being secured by eyes in said centerplates, and having their upper ends run through the arch A with washerand nut above for tightening up the rods. The suspension-rods 1 aresecured to the center-plate K and lower chords B, and thus serve assupports for the chords midway between the posts, and the rods J runfrom the center plate K to the arch A and serve to hold the arch againstbuckling upward, as well as to transfer a portion of the load on thechords to the arch. The rod L has its ends secured between the plates K,and is run through and secured in the web of post D by jam-nuts, thusholding said post from bending longitudinally at the center.

The advantages resulting from this construction will be more readilyseen on applying it to a long span of two hundred feet or more, althoughit can be economically used in spans of one hundred feet and over.

A two-hundred-foot span is ordinarily made with fourteen panels, ofabout fourteen feet length, and is usually twenty-five feet deep, sothat the center ties have a vertical height of about twenty-five feet infourteen feet, instead of running at the economical angle of forty-fivedegrees, and each girder requires thirteen posts.

If the eight central panels be made into four double .panels, as wouldbe done in applying this plan of construction, it is seen that four ofthe posts will be replaced by light suspension-rods I J, thus reducingthe number of posts to nine, that the three longest remaining posts willbe held at the center by rods L, thus halving their length and reducingtheir cross-section, and that the central diagonal ties will be laiddown at an angle of much nearer the economical angle, be-

sides being much reduced in total length, thus materially lessening thecost of the girder, and at the same time increasing its stilfness.

What I claim herein as new, and desire to secure by Letters Patent, is--l. The connection of the diagonal ties in a panel of a bow-stringarch-bridge with each other, and with the arch and chord of said bridgeat their intersection,substantially as and for the purpose specified.

2. The attachment of the center of an archpost with the connection ofthe diagonal ties at their intersection, substantially as and for thepurpose specified. v

As evidence of the foregoing, witness my hand this 5th day of August A.D. 1876.

JOB ABBOTT. Witnesses:

' ELVIRA SNYDER.

RUTH K. ABBOTT.

